Electric switch and contact structure therefor



Jan. 7,1930. 0. c. GARROWAY ET AL ELECTRIC SWITCH AND CONTACT STRUCTURE THEREFOR Filed Jan. 2, 1926 .25 contact member so arranged that each seglength to form a plurality Patented Jan. 7, 1930 UNlTElS STATES PATENT OFFICE,

DAVID C. GARROWAY, OF BELMONT, AND

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MASSACHUSETTS, ASSIGNORS TO CONDIT ELECTRICAL MANUFACTURING CORPORA- TION, OF SOUTH BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS ELECTRIC SWITCH AND CONTACT STRUCTURE THEREFOR Application filed January 2, 1926. Serial No. 78,818.

This invention relates to electric switches and has for an object improvements in the construction of contact members therefor.

A common type of contact member comprises a tube into which the cooperating contact member, usually a rod, is moved to complete the circuit. The tube is split "along its of separate segments or shoes, and acoiled annular spring encircles the segments to press them yieldingly against the rod.

When the switch is opened under heavy load it sometimes happens that the circuit-.

interrupting arc enters the space between two adjacent segments and burns and severs the spring, so that good pressure contact cannot be made when the switch is again closed.

7 It is an object of this invention to provide a segmental contact member of the type above set forth with spring-means to urge the seg ments against the cooperating contact *rod, the spring-means being so arranged that the circuit-interrupting arc cannot-readily gainv access thereto;

A further object is the provision of a split ment thereof is independently positively connected electrically in the circuit through the switch.

A further object of the invention is the pro vision ot a bell-type contact member and supporting means therefor so arranged that the contact member is self-centering on the cooperating contact rod, thereby to facilitate engagement between the two regardless ofsmall departures from absolute alignment.

A further object is generally to improve the construction and operation of electric switches and circuit interrupters.

Certain features ofthis invention are disclosed in a co-pending application of David C. Garroway, filed January-2, 1926, Serial No. 78,819.

Fig. llis a more or less diagrammatic representation of the separable'contact member of an electric switch in which this'invent-ion is incorporated.

Fig. 2 is a side elevation, partly in section, of the-stationary contact structure of Fig. 1, in which the invention is embodied.

Fig. 3 is a plan view of the contact structure of Fig. 2, the supporting bracket being broken away.

Fig. 4 is a section "along line 4-4 of Fig. 2.

Fig. 5 is a side elevation of one of the segments of the bell contact member.

As shown in Fig. l-the electric switch embodying the invention includes the station ary switch members 10 and the movable switch member 12. The movable switch member includes a cylindrical contact rod 14 which is extended vertically upward from a supporting bar 16 and is adapted to enter a stationarily-supported tubular contact 7 member or hell 18 carried by a stationary switch member.

The contact bell includes a metal tube which has aninternal vertical passage 20 extended from end to end thereof in which the contact rod 14 is adapted to be received and to make contact. The passage has an outwardly flared lower entrance 22 which facilitates entry of the contact rod into the bell and also serves to effect the lateral shifting of the bell into alignment with the rod, if the bell is initially displaced from suchalignment. The upper end ofsaid passage is also provided with an outwardly flaring end 24.

Said bell is supported in a bracket 26 which is fixed to and is in electrical connection with a stationary switch member 10. .Said bracket is formed or provided with an approximately' circular head 28 in which said bell is received. Said head is formed with a circular recess 30 in its top face and a wall 32 which closes the bottom of the recess. Said wall is formed with an aperture 34 therein through which the contact bell is extended. A cover plate 36 is disposed on said head to cbver the top of said recess and is provided with an aperture 38 through which said bell is extended. Said cover plate is secured removably in the aforesaid relation by bolts 40 which-extend through said cover plate and, are screw-threaded into said head. The contact bell' is provided. with a radiallyoutstanding annular flange 42 intermediate its ends, which flan e isdisposed within said recess-30 and is adapted to rest upon the bot- I thickness of the flange, so that the bell will be restrained against any material amount of vertical movement.

Said contact bell is slit radially from end to end in a manner to form a plurality of separate segments or shoes 44, three shoes being here shown. Means including spring elements are provided to urge said shoes inwardly toward their common center and said said spring elements are arranged to be concealed and shielded against the circuit-interrupting arm. Saidineans includes a ring 46 which is disposed within said recess and encircles the flange 42 of said contact bell. Said ring is provided with a plurality of radially inwardly directed pins 48 which have screwhreaded outer ends 50 which are screw-threaded removably into said ring. Said pins are received in radially inwardly directed recesses 52 formed in the shoes 44.

' As here shown, each shoe is provided with two recesses in which pins are disposed. Springs 54 encircle said pins and are received in enlargements 56 of said recesses and are approximately completely enclosed within said recesses. Th inner ends of said springs bear against shou ders 60 of said shoes and the outer ends bear against said ring 46. The arrangement is such that said springs tends constantly to urge said shoesinwardly toward the common center and thereby into firm contact with the movable contact rod 14 while the pins 48 serve to guide said shoes during such movement. The. springs are practically entirely enclosed within the shoes and thereby occupy positions inaccessible to the circuit-interrupting arc. ;The bottom wall 32 of the recess further shields said springs against contact with the circuit-interrupting arc and the hot gases resulting therefrom.

Said cover plate 36 is provided withan upwardly extended wall 62 which is terminated at its upper end in an inwardly-directed flange 64 whereby to form an enclosure or housing 66 about the upper position of the contact bell. Means are disposed within said enclosure by which each contact shoe 44 is independently and positively electrically connected with the bracket 26. Said meansin cludes a plurality'of flexible leads 68, two be:

.ing associated with each shoe. Said leads are secured to andconnected electrically with the shoes by means of screws 70. Slots 7 2 are formed in the flange 64and upper portion of the wall 62 of the cover plate adjacent each shoe and the leads are extended in pairs outwardly through said slots. The outer ends of said pairs of leads are reflexed'away from each other and against the wall 62,

andsprings encircling said pin and in which position they are secured by screws 74. This arrangement permits the bell to float within its supporting bracket, and permits independent movement of each shoe,

while maintaining positive electrical connectact member, and a housing in w ich said contact member and ring are received loosely and can move laterally in all directions.

2. A contact structure for electric switches including a floating tubular contact member having a plurality of independent segments, a ring encircling said contact member and floating therewith, and resilient element s connecting said segments and ring characterized by independently urging said segments toward each other.

3. A contact structure for electric/switches including a housing, a tubular contact member therein having a plurality of independent segments, a floating ring loosely received in said housing and encircling said contact member and adapted to move laterally in all directions, and pins carried by said rin which are received loosely in recesses in sai segments.

4. A contact structure for electric switches including a housing, a tubular contact member having a plurality of independent segments, a floating ring disposed loosely in sa1d housing and encircling said contact member, and pins carried by said ring which are received loosely in recesses in said seglments,

aving hearings on said segments and also on said ring.

5. A contact structure for electric switches including a tubular contact member havin a plurality of independent segments, am? a floating ring encirclin said contact member, resilient pressure-app lying elements independently connecting said segments and ring, said segments and ring also having loosely interlocking parts characterized by preventing undue relative angular .displacement between said ring and segments.

Ill

6. A contact structure for electric switches including a housing, a tubular contact member disposed therein having a lurality of independent segments provided with recesses therein, a floating ring loosely received in said housing encircling said contact member at said recesses, and compression springs contained in said recesses and having bearings against said ring.

7. A contact structure for electric switches including a tubular contact member havin a plurality of independent. segments provi ed with recesses therein, a ring loosely encircling said contact member closely and arranged in springs encircling said pins in said recesses and having bearings against said segments and said ring.

9. A contact structure for electric switches including a supporting member providin a pair of superimposed enclosures, a tubu ar contact member disposed loosely in both enclosures, said contact member including a plurality of relatively movable contact segments, resilient su porting means for said segments disposed 1n. the one enclosure, and flexible leads disposed mainly in said other enclosure and having connections with said,

segments therein.

10. A contact structure for electric switches including a supporting member providing a pair of superimposednenclosures, a tubular contact member disposed loosely in both enclosures, said contact member including a plurality of relatively movable contact segments, resilient supporting means' for said segments disposed in the one enclosure, and flexible leads disposed mainly in said other enclosure and having connections with said segments therein, said flexible leads extended externally of the enclosure andhaving means securing their extended ends externally to said sup- ,porting member. I

11. A contact structure for electric switches including asupportingmember having a recess therein, an apertured bottom wall for the recess, an apertured cover plate for the top of the recess, and a-tubular contact member extended through said apertures and having an outstanding flange disposed in said recess between said cover-plate and bottom wall, said contact member being free to float within said recess.

12. A contact structure for electric switches including a supporting member having a recess therein, an apertured bottom wall forthe.

recess, an apertured cover plate for the top of the recess, and a tubular contact member eX-' tended through said apertures and having an outstanding flange-disposed in said recess between said cover-plate and bottom wall, said tubular contact member having a plurality of independent contact segments, a ring disposed loosely within said recess abo ut said ange, and springs'connecting sald ring and segments;

13. A contact structure for electric switches including a supporting member havin arecess therein, an apertured bottom wall or the recess, an apertured cover plate for the topof the recess, and a tubular contact member extended through said apertures and having an outstanding flange disposed in said recess between said cover-plate and bottom wall, said tubular contact member having a plurality of independent contact segments, a ring disposed loosely within said recess about said flange and springs received in recesses in the flange section of said segments and having bearings against-said ring.

14. A contact structure for electric switches including a supporting member having a recesstherein, an apertured bottom wall for the recess, an apertured cover plate for the top of the recess, and a tubular contact member extended throu h said apertures and having an outstanding flange disposed in said recess between said cover-plate and bottom Wall, said tubular contact member having a plurality of independent contact segments, a ring disposed loosely within said recess about said flange, pins carried by said ring and extended loosely into recesses in the flange-sections of ,said segments, and springs received in said ments and said ring.

15. A contact structurefor elec tric switches comprising a plurality of associated contact shoes disposed side by side to form a tubular contact member, independent compression recesses and having bearingsagainst said segsprlngs acting independently on each of said shoes, and means including a floating abutments surrounding said contact shoes and cooperating with said compression springs to transfer pressure on one shoe through said springs to other shoes.

'16. A contact structure for electric switches comprising a plurality of cooperating and independently-movable contact shoes, inde-' pendent spring-pressure applying means for each shoe, and means acting upon application of pressure on one shoe to increase the spring pressure on another shoe'including a floating rigid ring surrounding said shoes and connecting said spring-pressure applying means.

17. An electric switch having a tubular contact member comprising a plurality of contact segments having independent resilient supports arranged to urge said segments together, acooperating contact member comprising a rod movable into and out of said tubular contact member, a housing within which said tubular contact member is loosely disposed, whereby it is free to move laterally to align itself with said cooperating contact member, and means including an abutment for said resilient supports loosely surround-' 18. A contact structure for electric switches including a housing, a tubular segmental contact member, and resilient means to support it yieldingly including compression springs received in recesses in each segment of said contact member, and relatively fixed abutment means for the similar ends of said springs received loosely in said housing and arranged upon yielding movement of said contact segments to cooperate therewith to completely enclose said springs.

19. A contact structure for electric switches including a housing, a tubular contact member having a plurality of independent segments received loosely in said housing, means independently to urge each of said segments toward the others, and means supported loosely in said housing independently of said contact member to shield said urging means from the circuit interrupting arc.

20. A contact structure for electric switches including a housing, a multi-part contact member having independent resilient means i to support the parts yieldingly, floating supporting means for said resilient means, said resilient means being disposed mainly within and enclosed by said parts. I

In testimony whereof, we have signed our names to this specification.

DAVID C. GARROWAY. CHESTER D. AINSWORTH. 

